The invention is concerned with the production of waistband interlinings.
It is conventional to produce waistband interlinings by cutting strips of appropriate length from relatively wide, continuous lengths of woven or nonwoven material. The interlinings are suitably cut from fill width piece goods in the wrap direction by cold shearing or by the use of a hot knife.
A disadvantage associated with this method of producing interlinings is that the cut edges of the fabric are rough. In the case of hot cutting a strip containing nylon or other thermoplastics material in the weft, or fill the edges become even more rough and brittle. When such a strip is inserted wholly or partially around the garment waistband, the weft threads, normally monofilaments, tend to protrude through the waistband shell fabric and may cause irritation to the wearer. When the interlining is a strip woven on a narrow loom, the return bights of the weft, i.e. the selvedge, tend to break, with the same undesirable protrusion of points which may penetrate the shell waistband fabric, abrade the same, and cause irritation to the wearer.
These disadvantages are overcome to a considerable extent by the process described in U.K. Patent Specification 1,213,957, (and U.S. Pat. No. 3,571,814) according to which a continuous bead is applied to each cut edge of the interlining. One method for applying the continuous bead described in Patent Specification 1,213,957 comprises continuously extruding a plastics composition onto the moving interlining strip. The continuous bead forms a finished edge which prevents the needle-like ends of the weft threads from penetrating or abrading the waistband shell fabric. This prevents the displacement of the weft threads. The material of the bead flows into the interstices of the interlining strip to unite the bead, wrap, and fills into an integrated whole.
While the method of the above-mentioned Specification works well, the production of an interlining strip in accordance with that method from a full-width fabric involves two distinct operations, namely cutting the strip from the full width piece goods and then extruding the edge bead onto it. It is an object of the present invention to provide a method of producing a waistband interlining having a "smooth edge" wherein the cutting of the interlining strip and the provision of smooth edges thereon are carried out in a single operation.
In its simplest form, the invention involves the melting of the fill yarns and the fusing or "smearing" of their molten ends into each other to form a continuous edge. Additional, the molten fill ends may also fuse with one adjacent warp, at least in places. Preferably, the fill ends do not fuse with any warp threads.
In general terms, the waistband interlining material comprises an elongated web of resilient, stiff woven fabric. The fabric has at least about 30 fill yarns of thermoplastic material per inch and no more than about 42 warp yarns of a high thermoplastic content per inch. The ends of the fill yarns at the elongated edge of the web have undergone fusing to each other and no more than one of the warp yarns.
The fabric of the waistband material incorporates a finishing on the woven warp and fill yarns. This finish typically takes the form of a thermoplastic material added, in a molten state, to the yarns and allowed to cool into a solid mass. An acrylic resin represents a convenient type of finish.
The finish on the fabric generally facilitates or even permits the formation of a fused, solid mass on the elongated edge of the web of fabric of the waistband material. This may result from the finish itself acting as a sort of adhesive to hold the yarns together during the fusion process to insure a solid continuum of thermoplastic material. Alternately, the application of the finish may serve as a tempering process on the yarns to make them more amenable to the ultrasonic fusing process.
The elongated edges on the web then form a fused, smooth mass formed from the ends of the fill yarns along the elongated edge. The fused mass may include all or part of one of the warp yarns. In the prefered case, however, the edge will result from the fusion of only the ends of the fills and will not include any material from the warp yarns.
Limiting the involvement of the fused edge to one and preferably no warp yarns results in the utilization of a simpler manufacturing process and equipment. To involve more than one warp yarns requires additional energy to provide the required fused mass.
Further, involving one or no warp yarns produces a smaller, smooth edge which has a width no greater than that of the fabric itself. Furthermore, avoiding the involvement of a plurality of yarns results in the removal of less of the original woven fabric from the final product; less of it disappears by melting under the ultrasonic knife.
Additionally, avoiding the involvement of many yarns into the edge provides a less expensive manufacturing process. The material may move through the ultrasonic cutter faster. Further, removing less product permits the greater utilization of the original fabric.
Moreover, the resulting interlining, with the thin fused edge, appears less likely to crack since it has greater pliability. Further, it allows the interlining to better retain its shape from one edge to the other since the fusing has had less of an effect upon the fill yarns.
A waistband assembly will then include a shell fabric of a garment such as a pair of slacks having an inwardly folded edge. A resilient woven textile strip as described above sits positioned within the fold of the shell fabric.
The warp of the woven strip will have a high thermoplastic content and often includes no more than 42, and preferably 40, yarns per inch. The warp may include 20.5 one hundred percent polyester spun yarn.
The fill, running transverse to the warps, includes relatively stiff thermoplastic monofilament yarns and at least one smooth edge which has a position adjacent to the fold in the shell fabric. The fill will typically display approximately 30, 33 or more picks per inch. The fill may have a composition of polyester or of nylon.
The smooth edge of the textile strip results from the fusion of the fill ends and, occasionally, not more than one of the warps; most desirably, the edge will not involve any warp for the majority of its length. The resulting fused edge of the strip will appear smooth and should preclude the yarns of the fill from disengaging themselves along the smooth edge. The fusion most conveniently results from the ultrasonic cutting of the strip in the direction of the warp yarns.
The precise configuration of the continuous edge formed on the cut fabric is controlled by various factors. These include the speed of traverse of the material past the sonic unit, the shape of the pressing element, or knife, the amount of ultrasonic energy applied, and the degree of cooling, both to the horn and above and below the fabric beyond the pressing element.
The making of the waistband interlining involves first weaving a fabric having not more than 42 warp yarns per inch and at least 30 fill yarns per inch. The fill yarns have a thermoplastic composition . The manufacturing then continues with the placement of a thermoplastic finishing on the woven fabric.
Lastly, the fabric undergoes an ultrasonic cutting along lines substantially parallel to the warp yarns. It should produce a fused edge from the ends of the fill yarns along the cuts and involve no more than one warp yarn.
A machine for producing waistband interlinings using the method of the invention suitably comprises one or a number of stationary pressing elements positioned above one or more horns connected to ultrasonic generators. The machine also comprises means for feeding the fabric between the pressing elements and horns, and means for drawing off cut fabric.
The machine is operated such that the molten thermoplastics material of the weft between each pressing element and associated horn forms a bead which "bridges" one monofilament in the weft to the next, and, on occasion, fuses also into the adjacent warp or wale.
Various shapes of pressing elements may be used, depending upon the precise configuration which is required for the continuous edge. Preferably the diameter of the edge will be no greater than the thickness of the fabric in order that no ridge will appear on the waistband shell fabric during garment wear.
The pressing elements are suitably made from steel and subjected to a hardening process. The horn of the ultrasonic generator is suitably manufactured from titanium and carbide-tipped steel.